Piston enlarging machine



Dec. 8, 1953 Filed Dec. 20, 1948 H. M. OLSON PISTON ENLARGING' MACHINE 4 Sheets-Sheet l \NVENTYOR HOLLY OLSON ATTORNEY$ Dec. 8, 1953 H. M. OLSON 2,561,643

PISTON ENLARGING MACHINE Filed Dec. 20, 1948 4 Sheets-Sheet 2 NVENTOR HOLLY'M. 0LON ATTORNEYS Dec. 8, 1953 H. M. OLSON 2,661,643

PISTON ENLARGING MACHINE Filed Dec. 20, 1948 4 Sheets-Sheet 3 M121. Houwv M. OLSON Dec. 8, 1953 H. M. OLSON 2,661,643

PISTON ENLARGING MACHINE Filed Dec. 20, 1948 4 Sheets-Sheet 4 Ymmk; \@9 64 SWIT H g M NVESTOR HOLLY M. LSON Fuar H.

ATTORNEYS Patented Dec. 8, 1953 PISTON ENLARGING MACHINE Holly M. Olson, Muskegon, Mich, assignor to Sealed Power Corporation, Muskegon, Mich., a corporation of Michigan Application December 20, 1948, Serial N 0. 66,203

'7 Claims. 1 The present invention relates to a novel and very practical mechanism for rapidly resizing worn pistons. H

Pistons used in internal combustion engines, after service for a considerable time therein, become worn at their peripheral surfaces and it is desirable that they be reconditioned, that is. brought back as nearly as possible to their original dimensions so as to have their outer surfaces conform as nearly as may be to what they were originally or to the cylinders in which operating, this for the purpose of better fitting the cylinders in which they are installed, to prevent piston slap and other noises and to maintain an effective compression of the fuel charges which are drawn into the cylinders above the pistons.

With the present invention, it is an object and purpose to provide a machine for peening and upsetting the piston at its inner sides and adjacent the wrist pin bosses therein, to thereby elongate sections of the piston surrounding said bosses and in this manner restore a proper size to the piston with little or no change of the worn-in contours. It is desirable that the restoring to a proper fitting in a cylinder shall be by enlarging the piston on its worn diameter, through stretching and elongating the surfaces supporting such worn diameters. These are the surface areas in line with the wrist pin holes or openings. Such change of the metal, in effect stretcnmg 1t, accomplishes a desired resize with the least amount of distortion to the wrist pin alinement and in the smallest amount of time. Only small sections of the inside surfaces in line with and adjacent the wrist pin holes are acted upon.

A further object of the invention is to provide a machine in which a plurality of pistons may be simultaneously enlarged, in practice preferably two pistons being simultaneously enlarged. The principle upon which the machine operates is to strongly oscillate the piston with its open end closed and in the space within the piston and held therein, a plurality of impact members are loosely positioned. Such impact members preferably in practice may be of star-form each having a plurality of pointed projections. With the oscillation of the piston the impacting members are thrown back and forth and strike against selected areas on the inner sides of the piston skirt which preferably are open to the impact of the impacting or peening members only, the remainder of the interior of the piston being shielded and guarded so as not to be subject to such peening impact. The oscillation is rapid and upon attaining the necessary speed, the imv viding of novel mechanism which incorporates a flexing action to the mechanism which oscillates the pistons which acts as a shock absorber of inertia, and also gives a rebound action which intensifies the impacting blows of the star mem bers of other impacting objects used, thereby resulting in increased speed of operation and a more rapid resizing of pistons at reduced oscillating speeds.

Still further objects of the invention are to provide a machine which, under the control of an operator thereOf may be set in motion by manually closing an electric circuit for energizing an electric motor which drives the mechanism, and incorporating in such circuit a timing switch which may be pre-set for the time that a piston or a plurality of them are to be subjected to the resizing impacts, the machine stopping operation after such preselected time has gone by. And with the machine also which has a capacity of simultaneously resizing two pistons, the machine may be adjusted and conditioned for resizing one piston only selectively of either of the two piston resizing units which are provided, one for each piston.

A still further object of the invention is the I provision of an automatic moving of a guard in pact members of small size and weight will be v front of a manually operable holding screw used in clamping a piston in place, and operatively associating and connecting it with a counter. When the guard is in its operative position, a piston cannot be removed until the guard is moved back to its inoperative position, which act of moving automatically requires the register of the count of pistons which have been processed on the machine, a guard and a counter being supplied for each of the piston resizing units of the machine.

These and many other objects and purposes and novel mechanism for attaining them will appear and be understood, from reference to the following description of a practical and commercially produced embodiment of my invention, shown in the accompanying drawings to which such description pertains, and in which drawings,

Fig. 1 is an end elevation with parts of the enclosing housing portions of the machine broken away and with some parts shown in section for a better disclosure of the resizing mechanism.

Fig. 2 is an enlarged elevation and partial vertical section through a piston carrying saddle,

one used with each of the units of the machine, for releasably securing a piston to be processed in place.

Fig. 3 is a horizontal section, substantially on the plane of line 3-3 of Fig. 2.

Fig. 4 is a vertical :section 'therethrough, the piston having been turned from a vertical to an inclined position by rotating it about the axis of its wrist pin bosses;

Fig. 5 is a fragmentary transverse vertical section, from one side to the other, of the upper portion of the machine substantially at the plane of line 5-5 of Fig. 1.

Fig. 6 is an end elevation of the manually operable hand lever for controllingthe starting of the machine.

Fig. 7 is a fragmentary vertical section, substantially on the plane of line 'I-| of Fig. 5.

Fig. 8 is a fragmentary transverse vertical section, the plane of the section being through the front of the machine "shown in Fig. 1 and in front of the guards preventing piston disconnection, substantially on the plane of line 8--B of Fig. 1.

Fig. 9 is a vertical section from front to rear of the upper portion of the machine shown in Fig. 1, showing the guard operation andcontrol, associated with which is the starting control mechanism for the machine, the plane of thesection being substantially that shown inline 9--'9 of Fig. 8.

Fig. 10 is a vertical section showing the detail of the guard operating and switch closing plunger shown in elevation in Fig. 9, and

Fig. -11 is a diagram of the electric circuit, including the driving motor and timing switch and the breaks in the circuit controlled by manual operation of the hand lever of Fig.6.

Like reference characters refer to like parts in the different figures of the drawings.

In the construction of the machine, a lower supporting structure, generally indicated at I, of a proper height and base area, is surrounded at its upper end by-a band 2'whic'h at the front and underneath the piston resizing mechanism is downwardly inclined as at 3 where, as later described, a conveniently accessible-timing switch is carried.

The piston resizing mechanism is above the upper end of the lower support I. It includes a cast frame having spaced parallel vertical sides 4, a vertical back 5 and a shorter vertical front 6; and as shown in Fig. 5, there may be a horizontal bottom extending between the sides 4 as indicated at M. The major portion of the open upper side of this frame is covered'by a cover 1, at the front of which a hinged closing lid 8 is mounted, shown in closed position in Fig. 1, which may be raised and lowered by a handle 9. In

its closed position the lid is releasably latched in place by a manually operable latch 10. When the lid is lifted and turned back upon the cover I, the pistons may be entered through the opening provided for attachment to the mechanism for resizing, and are also accessible for removal after the resizing has taken place.

Between the front and rear sides 6 and 5 a vertical partition ll extends between the sides 4. A sleeve I2 for each resizing unit extends through the partition H and through a rearwardly extended bearing flange I la, being rotatable therein. At its rear end it is provided with a worm gear l3. In front of the partition H the sleeve I2 has a continuous annular groove.

A finger l4 fastened to the front Side of the partion H extends in said groove to hold the sleeve against longitudinal displacement.

A flat bar 15 is slidably mounted upon and passes through the sleeve 12, at its upper and lower edges being guided in grooves cut longitudinally and interior-1y of the sleeve (Figs. 5 and 7). Such bar at its front end has a rod l6 of short length riveted or otherwise permanently connected to it. The rod [5, as shown in Fig. 2, has an extension 11 of smaller diameter extending forward therefrom. The extension I! at its front end portion is interiorly bored and threaded as shown, and from the threaded opening an axial passage extends rearwardly through tbhe rgd I1 and the rod Hi to the front end of A jaw 18 adapted to engage a side of a piston has an opening for passage of the rod I! through it, and may be key connected with the rod 16 by means of a key 19 for releasable holding of the jaw in connection with said rod it. When connected therewith it is impelled to move with the rod [6 in turning movements about its axis as will hereafter appear.

A piston 20, having a closed upper end or head and an open lower end, is inverted in position and is passed over the rod l1 until a side thereof comes against the jaw l8, said jaw and piston being in substantially vertical position. Such rod section I? passes freely through the wrist pin openings of the pin bosses 21 which project into the interior of the piston, such being common and conventional piston structure.

A second clamping j aw 22 has a permanent yet swivel connection with a handle 23 from which an exteriorly threaded screw 24 passes through the jaw and is screwed into the interiorly thread ed end portion of the rod II. In addition a pilot rod 25 integral with the screw 24 enters the axial openings of the rods H and carries therethrough into the like opening in the rod 16 as shown in Fig. 2. It is evident that the piston may be releasably clamped between the jaws l8 and 22 and firmly connected with the bar i5 to move therewith.

A sleeve '26, preferably of rubber or rubber-like material, is located between the adjacent ends of the wrist pin bosses 2! before placing it over the rod I! which passes through the sleeve. After the piston is secured in place impacting members 21 are dropped into the inverted piston. Such impacting members may take a variety of forms, but in general are of relatively small size and preferably will have pointed projections, as in stars of metal, such as shown in Fig. 2. In practice with a normal size of piston, about a dozen of such star impacting members are dropped into the piston before the open end of it is closed. It is of course apparent that pistons of various diameters and lengths are adapted to be releasably carried in the saddles provided for them in the machine of my invention.

A rod 28 is permanently secured at one end to the upper side of the rod 16 extending vertically therefrom. A cover plate 29 of fiat metal for the open end of the inverted piston 20 is detachably connected with an arm 36 which has a sleeve 3| slidably mounted on the rod 28 to be adjustable thereon to different positions. By adjusting said sleeve the cover plate 20 may be brought to close the open end of the piston and by a thumb set screw shown in Fig. 2 sleeve 31 is secured to the rod 28. The detachable connection of plate 29 to the arm 3'0 is for the purpose of supplying covering plates 29 f different di amet'ers for different sizes of pistons.

Inasmuch as it is in general desirable that the impact of the star members 21 shall be confined to certain areas of the interior of the piston skirt, preferably a guard of sheet metal, shown at 32, is inserted in the piston before placing the star members 21 therein and before closure by the cover plate 29. This uard of substantially U- shape and having legs between the head of the piston and the closure place 29 (Fig. 4) will confine the areas struck or impacted against to those between said legs 32 and, therefore, around the wrist pin bosses 2 I.

At the opposite or rear end of the fiat bar I a fixture 33 is secured which includes a cup-like head exteriorly threaded, in which a collar or sleeve 34 is mounted for relative free turning movement. An exterior nut 35 having an outer side with an opening in it, screwed onto the exteriorly threaded cup portion to retain the sleeve 34 against disconnection (Fig. 7). A short rod 36 has a pivotal connection by a cross pin 34a with the sleeve 34 (Fig. 7) and at its opposite end (Fig. 1) is connected with two oppositely bowed or curved fiat metal spring members 31, the curved or bowed portions of which are of substantially semi-circular form and which in turn are connected to an alined short bar 38. The outer or rear end of the bar 38 has a pivotal connection with a crank 39, integral with which is a weight 40 connected to a driven shaft 4| suitably carried on the frame structure. A pulley 42 on the shaft 4| is driven by an endless belt 43 from anelectric motor 44 which may be housed below in the housing From the construction thus far described, it is evident that with the motor running the bar I5 is rapidly reciprocated. The piston is oscillated back and forth in the direction of the length of said bar i5. Spring members 31 are alternately bowed outwardly and snap inwardly under the inertia forces resulting from the stopping of the piston at each end of each of its oscillatory movements. The impacting members 21 within the piston shuttle back and forth between the sides of the piston and with the rapid reciprocation which takes place, do not drop by gravity but remain in suspension moving back and forth between opposite interior side areas of the piston skirt and striking thereagainst with a considerable force, thereby peening the surfaces struck against, and elongating such surfaces and the metal outwardly therefrom and restoring the piston skirt to-the enlarged size wanted. In practice and as about to be described, the piston, when such oscillatory movement imparted to it takes place, is not in an inverted vertical position as in Fig. 2, but has been turned to a position closely approaching horizontal or as in Fig. 4. A transverse shaft 45, extending from one side 4 to the other side 4 and through such sides is rotatably mounted with suitable thrust bearings as shown in Fig. 5. Between its ends a worm or spiral gear 46 meshes with the gear i3.

each other within the housing, provided by the frame and covering for it, of the machine. theouter end of the sleeve 41 a collar 49 is fixed which has a recess in one side. The shaft extends outwardly a distance beyond such collar and is equipped with a like collar 5! having an alined like recess 52 therein.

A handle 53 for manual turning of the shaft 45 and sleeve 41, either of them independently or both together, is loosely mounted on shaft 45 between the spaced collar 49 and 5|. There is a pin 54 projecting radially at its shaft mounted end. A flat plate 55 with a horizontal slot 56 for the pin 54 to pass therethrough is secured to the handle 53. Between the plate and the handle a fiat bar 51 is slidably mounted to which the pin 54 is connected. The bar 5'! is movable within the limits described by the slot 56 and the pin 54 therein, so that at its ends it may extend into both of the recesses 5!) and 52 of the two collars 49 and 5| (Fig. 5), or it may be moved so that either of the recesses 50 or 52 may have.

the adjacent end of the bar 51 in it, but the opposite end of the bar will be moved out of the other recess so as to connect the handle 53 with either the shaft 45 or the hollow shaft 41; and only the shaft with which hand lever 53 is connected will be rocked by it. Therefore only one of the piston resizing units may be operated at a time if that is wanted and either of the units may be selected for such operation. Furthermore, both of the units may be operated simultaneously when the shaft 45 and the hollow shaft 41 are both connected with the shaft 43 for simultaneous operation, as is shown in Fig. 5.

It is apparent that on moving the handle 53 from its back position shown in Fig. 1 in a forward direction, the sleeve E2, the bar l5 slidably connected with it and the piston carrying saddle at the front end of the bar I5 will be turned to change the piston from vertical position as in Figs. 1 and 2, to an inclined position as in Fig. 4. Such movement occurs through the gearing connection of the worm gears 46 and 48 to their complementary gears l3. The extent of movement of the handle 53 will be governed by limit stops, one of which is shown in Fig. 5.

On the shaft 45, and also on the hollow shaft 41, a cam 58 best shown as to its form in Fig. 9 is permanently secured. One end of a rod 59 for each cam slidably mounted in a holding sleeve 60 therefor bears against its associated cam. Thesleeves 60 pass through the partition H. .The front ends of rods 59 engage each against a guard iii of the shape best shown in Fig. 9, pivotally mounted at their rear ends at the front of partition I! and terminating each at its front end in an upwardly turned leg Bla. Such leg Bla when a guard is in horizontal po-' sition, having been moved to such position by forward movement of thepin 59, comes ahead 01' in front of the screw actuating member 23 which is recessed to provide a socket to receive a socket wrench. When raised to horizontal position, instead of the downwardly inclined position shown in Fig. 1, the member 23 cannot be turned sufliciently to disconnect the clamping jaw 22 for removal of a piston.

When the shaft 45 is rocked by swinging hand lever 53 in a forward direction, the cams 58 are turned to move'the rods 6!] forward and each lift its associated guard 6| to the upper position shown in Fig. 9. Therefore, the lifting of a guard occurs substantially simultaneously with the 11;. turning of; an associatedpiston.fromthe vertical positionin. Fig. .2 to the -inclined. position. in Fig. 4.

Starting the electric motor Misalsocausedby such forward movement. of the; hand: lever 53, an. electric circuit being'closed. A rod-.62 is secured to the. rear end portion of eachrod 59., the guide sleeves 60 being slotted length-wisein. their upper. side topermit movementof said rods Elwith the rods- 58. In the electric circuit two contacts 6-3 and B4-are. included, otwhich the contact 64 may be connected with. red $2 tomo-ve therewith, while contact 63 willbe relatively fixedandtoward and. away. fromwhich the contact 6.4 moves with the movement ofv rod. 62. A spring 65.- associated, as shown in Fig.v 9,,with the rod 62-. and the supportv for suchrod, under compress'iontends. to move the rod 62 toseparate the contact 64- connected therewith from the fixed contact 63?. But when the associated. cam 58 is moved to the .positionas. in Fig. 9 to thereby move rod. 5.9 ina forward direction and rod 62 with it, spring 65. is further compressed and the contacts which close an electric circuit arebrought together.

The electric circuit diagram shown in Fig. 11, shows that a circuit wire 6% from one side of the motor leads to a timing switch 51 which. is conveniently mounted on the previously described inclined shelf. at the front of the machine (Fig. 1) The other wire 68 leading from the motor connects with the two contacts 63. Wires 69 joining together in a single wire leading to the other side of the timing switch 61 are connected with the other contacts 64. With the timing switch set to close the circuit, and hold it closed for a predetermined period of time, the motor 44 will run upon bringing together eitheror both of the contacts 63 and 64. The closing of both of such circuit breaks or gaps will occur when the handle 53 is connected with both collars 49 and (Fig. 5) and the handle is rocked to its forward position. The circuit will also be closed with the handle connected toeither collar 49-01- 5'lon rocking the handle to its forward position.

A counter for each of the piston processing units is mounted at 10 at the front of the machine (Fig. I). A rocking arm H of the. counter has a link I2 secured thereto and leads to the rear to a hand lever 13 secured between its. ends to a rod T4. passing through and mounted for rocking movement in a mounting sleeve. 15, one of such sleeves extending through each of the. sides. 4 and each sleeve at its outer end having a disk. head 1-6 which has a pin connection to its adjacent side 4 to hold the sleeve. from rotative movement. Rod 14 at its inner end has an arm H fastened thereto. From the arm 11 a.- short in 18- extends. in an outward direction. The inner end portion of each sleeve, isfiattened at a side to make a flat surface 19 (Figs. 8 and 9). The pin 18, moving with the rod TI, strikes at two. spaced apart points on the surface 19 thereby limiting the arc of movement of. the arm 11'.

When the guard 6| on either or both of the resizing units is moved to its upper position (Fig. 9) the counter spring, the. detail ofwhich need not be disclosed as it is old and well known, causes the arm H of the counter to swing clockwise (Fig. 1) thereby turning the handle 13 substantially to a vertical position underneath its associated guard 6|, as in Fig. 8. At the end of a piston processing operation, when the time controlled by the timing switch 61 has resulted in interrupting the circuit of the electric motor M, followed by a.- pushing of lever 53 back to its initial position (Fig. 1), the guards will not return by: gravity-to. their 'IOWGIE'QOSILUQDS until. the arms 11 under them havebeenloweredby handle; op. eration of. thehandle 13.. Such handle operation from: a substantially vertical position. to. that. shoWninF-ig. 1-. will actuate the counter I0. Until; such. manual release,v which must operate. the. associated-counter, occurs, it will. be impossible-to: remove theprocessed piston as its securing member 23: cannot be reached for: unscrewing and. 1 6,-- moval until the. guard end. Iii-av of. its associated. guardifi lehas beenlowered.

In; the use; of. the.- machine, by lifting the lidat. 8.. pistons may. be secured at the outer ends of the reciprocating or oscillating shafts. consisting; or

- the partsebetween, therod l6. atone end and the bar 3.8. connecting the, other endof eachQf; said shaftsto. its crank 39. If. one: piston only is, to; beprocessed; it. will; be clamped. in. the shuttle for; holding, it on one of theshafts; andthe handle53 moved: in. the proper direction. to connect with one onlyof the collars. 49. or 5!. The-openuppen end ofthe inverted piston is closed by the-plate. 2 9;. the small impact or. peening members 21 having, been placed within the piston and, r zrefer v ably, the; guard 32 located; therein as shown in Figs. and Thetimethat a piston: processing; peration. 15:13.0 continue-Will: be predetermined by setting the timing. switch 10..

0h rocking. the lever 53. in a forward: direction, motor 44. is. started.- and: thepiston. or; pistons are; rapidly oscillated back andiorth at; a desired ire.- quency... The; impact; members; 21' will; through: such reciprocating or; shuttle action, bombard, sections at the inner sides; or the piston. within.

' the plane of oscillation, the piston having been turned from vertical. to; substantially the position, shown. in- Fig. 4 when the lever- 53. isforwardly moved. Such. shuttleactionof the impact memhas on the inside'of, the piston, directed against. prescribed sections, elongates and stretches the metal, resulting in a desired enlargement of the piston. The enlargement wanted is; predeter-. mined and, the desired size obtained and con.- trolled by the time to which the pistons are exposed tothe action of the impact members. The, rebound actionof. the impact members, set up: by proper oscillation. frequency, obtains; a speed of movement of such members such that a suspension is: reached and the, impact. members moved back and forth and strike the piston at substantially opposite sides thereof. By proper design and positioning of the cams 58, the. shaft 45 and/orthe surrounding hollowshaft 41 may be turned partially without breaking, the. electric circuit, to; the motor so thatv the piston may be turned about. the horizontal position, the more the impact. members will strike opposite. sides of the piston with a full. length of movement, and the more turned toward, vertical position will the impact. members, due to gravity, tend to flow to the, lowest portion ofthe. piston. Thus anyportion or; section; of piston is under control for resizing by the position in which the piston is 10- cated, while subjected to the impact of said members 21..

The machine when loaded and set in operation under high speed, causes the impact members in their shuttle. action to strike the inner surfaces of the piston, with intense blows. Such blows take place the instant the connecting rod passes dead center and. starts its return stroke. Such impact action is intensified by reason of the resilient members 31 in the. length of the connecting rod. with a flexing in opposite directions thereof... and snap return action which is a func- 9 tion of the inertia of the oscillating parts, so that the impact blows are intensified, thereby producing the desired resize at reduced oscillating speeds.

In practice the electric timing switch at 19 is normally set for about five seconds for each .001 inch of piston enlargement. The operation is very rapid and the machine gives full and satisfactory performance. The count, which is made imperative by means of the guard structure insures that an accurate count of the pistons resized will be maintained.

The invention is defined in the appended claims and is to be considered comprehensive of all forms of structure coming within their scope.

I claim:

1. In a machine of the class described having a horizontal shaft mounted for independent or simultaneous turning and longitudinal reciprocating movements, and means for rapidly reciproeating said shaft in the direction of its length, said means having a relatively rotatable connection to one end of the shaft, the improvement comprising a clamping member adapted to be positioned at the opposite end of the shaft, said shaft having a. reduced diameter extension at said end, and the clamping member having an opening through which said extension passes, a second clamping member spaced from the first clamping member, and screw threaded means carried by the second clamping member having releasable screw connection with said shaft extension, said extension and screw threaded means being adapted to pass through opposite wrist pin bosses of a piston.

2. The elements in combination defined in claim 1, and a post connected to and extending outwardly from said shaft at right angles thereto, located adjacent the first mentioned clamping member, an arm mounted on said post adapted to extend over the open end of a piston held between the clamping members, and a plate secured at the inner side of the arm, of a size to cover and close said open end of a piston between the clamping members.

3. The elements in combination defined in claim 1, and a second shaft mounted'for rocking movements about an axis perpendicular to the axis of rotation of the first shaft, gearing connections between said shafts and means for manually turning the second shaft about its longitudinal axis for controlling the times and extent of turning of the first shaft.

4. In a, machine of the class described, a vertical support, a sleeve rotatably mounted on said support, a plate passing through said sleeve and support, said sleeve having opposed longitudinal grooves in which the edge portions of the plate are slidably received, a divided shaft, the end portions thereof secured to opposite ends of the plate, a gear on said sleeve, a second shaft, means to manually turn the second shaft, a gear thereon meshing with the first gear, a piston clamp at one end portion of said first shaft, a crank connected to the other end portion of the first shaft in rotative relation thereto and means for operating the crank arm to reciprocate said plate in the sleeve.

5. In a machine of the class described, a vertical support, a plate passing through the support, means mounted on said support for slidably mounting the plate, a crank arm, a driven shaft, means for connecting the crank arm at one end to said shaft at a distance radially from the shaft, pivotal connections between the opposite end of the arm and one end of the plate, and a piston clamp connected to said plate at its opposite end including two spaced clamping members between which a piston is adapted to be placed, said clamp having means adapted to pass through wrist pin bosses of a piston for releasably connecting the clamping members and for drawing said clamping members toward each other or moving them apart.

6. The elements in combination defined in claim 4, said crank arm comprising two aligned parts having adjacent ends spaced from each other, and spring means between adjacent ends of said aligned parts normally tending to maintain said parts separated from each other and yieldable to permit the adjacent ends of said parts to approach closer or separate farther than said normal spacing thereof.

7. In a machine of the class described having a vertical support, a member slidably mounted on and passing through the support, and means connected to said member at one end thereof for rapidly reciprocating said member, the improvement comprising a rod secured at its opposite end in general alignment therewith, said rod having a terminal portion of reduced diameter axially bored from its free end substantially to said member, and interiorl screw threaded from its free end portion for a distance, a piston clamping member having an opening through which said reduced diameter portion of the rod passes, a second clamping member adapted to parallel and be spaced from the first clamping member, an exteriorly threaded screw rotatably mounted on and at the inner side of the second clamping member adapted to screw connect with the interiorly threaded outer end portion of said rod, and means exterior of the second clamping member for operatively turning said screw, said screw having a pilot rod extending from the inner end of the screw for passing into the axial boring of said rod, said reduced end portion of said rod and said screw when together connected being adapted to pass through the aligned wrist pin bosses of a piston located between said clamping members.

HOLLY M. OLSON.

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